NEW DELHI, April 2 (Thomson Reuters Foundation) - Indian politicians who make bigoted comments should be punished by their parties, activists said on Thursday, after a government minister became the latest parliamentarian to be accused of racism and sexism.

Minister of State for Micro, Small and Medium Enterprises Giriraj Singh has under fire for remarks made in reference to Sonia Gandhi, the Italian-born leader of the opposition Congress party and widow of former prime minister Rajiv Gandhi, who was assassinated in 1991.

"If Rajiv Gandhi had married a Nigerian lady, someone not white-skinned, would the Congress have accepted her as its leader?" Singh said during an off-the-record meeting with reporters, which was secretly filmed and broadcast on Thursday.

The comments sparked outrage among Congress supporters who clashed with police in the capital on Thursday outside the headquarters of the Bharatiya Janata Party (BJP), the dominant party in the coalition government.

Nigeria's High Commissioner O.B. Okongor said the remarks were "unacceptable", while Gandhi said she would not react to people with a "narrow mindset".

Singh has apologised and the BJP has attempted to end the controversy by condemning the comments, but activists say political parties need to act against bigotry.

"These kinds of derogatory remarks are being made every day. The politician apologises and then the matter is forgotten. It's unconstitutional and promotes values which are destructive to the lives of women and girls," said Kavita Krishnan, secretary of the All India Progressive Women's Association.

"Political parties should have a basic code of conduct which can subscribe some kind of penalty."

Sexist slurs made by politicians across India's political landscape are commonplace, yet few result in punishment.

On Tuesday, local media reported the most senior official of the coastal state of Goa as telling striking nurses not to protest in the sun as it would make them darker and ruin their marriage prospects. Chief Minister Laxmikant Parsekar has denied the reports.

Last month, Sharad Yadav, president of the Janata Dal United Party, was slammed for commenting on women's bodies and skin colour during a debate in parliament on an insurance bill.

"The bodies of women from the south are as good as they are beautiful. The women in our region are not that good as those (in the south)," said Yadav, who was later forced to apologise for his comments.

Experts say deep-rooted patriarchal attitudes in India have led to widespread abuse against girls and women including rape, dowry murders and discrimination in education and employment.

The gang rape and murder of a woman on a bus in Delhi in December 2012 jolted many Indians out of apathy and brought gender equality into the spotlight.

But activists say their efforts are set back each time a senior political figure makes a derogatory remark.

"These guys are representing the country," said Ranjana Kumari, director of the Centre for Social Research. "They are supposedly elected to guide us towards a better society, towards a more equal society." (Reporting by Nita Bhalla; Editing by Katie Nguyen)